MISSISSIPPIAN ROCKS OF NORTHEASTERN OKLAHOMA 623 



is little sand in the formation the limestone is thin bedded and 

 platy. The surfaces of the thin plates are usually covered by 

 fossils in a more or less weathered condition; bryozoa are par- 

 ticularly abundant but are commonly poorly preserved. 



The thickness of the Pitkin in the Pryor quadrangle is seldom 

 over 20 feet and is usually less. From the middle of the quad- 

 rangle northward the Pitkin is locally absent, and the sandstones 

 of the Pennsylvanian lie upon the shale of the Fayetteville, or in 

 some places, upon the limestone about the middle of that formation. 

 In such cases the basal portion of the Pennsylvanian sandstone is 

 conglomeratic, containing pebbles of limestone up to an inch or more 

 in diameter. The Mississippian-Pennsylvanian unconformity is 

 thus very noticeable in the Pryor quadrangle, although it is not 

 evident in the quadrangle to the southward. As noted in a 

 previous paragraph, the correlation of the Pitkin in the Vinita 

 quadrangle is in doubt. The topmost of the four limestones in 

 this vicinity is probably the Pitkin. In the paper previously men- 

 tioned Siebenthal refers to the Pitkin as being present in the Wyan- 

 dotte quadrangle, but gives no details concerning it. The section, 

 however, is known to be very similar to that of the Vinita 

 quadrangle. 



The fauna of the Pitkin is very similar to that of the limestones 

 of the Fayetteville. Archimedes is very abundant and the Hme- 

 stone was called the Archimedes limestone in the older reports of 

 the Arkansas survey. The bryozoa which occur so abundantly in 

 the formation in the Pryor quadrangle have not been studied as yet. 

 The fauna is undoubtedly very similar to that already listed from 

 the Chester limestones in the Vinita quadrangle, which may be in 

 part from the Pitkin horizon. 



SUMMARY 



The Mississippian area in Northeastern Oklahoma is continuous 

 with the Ozark region of Missouri and Arkansas. The section 

 includes the Boone formation, unnamed limestone of Chester age, 

 Fayetteville shale, and Pitkin limestone. The Boone formation 

 and chert is from 100 to 350 feet thick and ranges in age from 

 Kinderhook to Keokuk. The Kinderhook is represented by shale 



